The V8 Owners Forum -

going over the datalog from last night and we have noticed at 6230rpm the injectors are running 94%,
so its looking like im rinsing everything out of these ones now, the duty cycle doesn't do anything manic so they are still ok to use, but this is as far tune wise these babies can go,
My current ones are Bosch Motorsport 440cc injectors, any recommendations????

63lb mototrons aka siemens deka's

(i'm sure steve and i reccomended these the last time this was dicussed)

First off check and log fuel pressure. No need to spend money just yet.

But yes the Siemens are great little injectors and wont break the already broken bank.

I can't remember these being mentioned before
just been looking on eGay and can find 60lb (630cc) but not 63lb ones, any links please???

looks like it was 60lb ones:
http://www.mez.co.uk/turbo7.html
If you zoom in you can see they are also marked as mototrons, part number is inj-gas-006

Worth checking your fuel pressure as Steve says, as I noticed mine was dropping by 10psi when it was on the dyno, meaning my injectors were also hitting 95%. So I have added a second fuel pump / feed and bought bigger injectors!

I also changed over to the Thor fuel rails too, as these are much fatter and they are split into 2 banks, so this gives me a much larger capacity. The hotwire fuel rail means the odd bank (especially cylinders 5+7) could run low on fuel compared to the even bank when the injectors are squirting massive amounts of fuel.

Think of 500cc / min x 4 = 2L/Min of fuel before its even got around to the odd bank, so 3.5L /Min before cylinder 7.

So I've added an infeed to each of the Thor fuel rails, meaning one pump feeds one bank and the other pump feeds the other bank. The other end of the fuel rails will go to a single pressure regulator.

The old injectors were 500cc / min, the new ones are 600cc, so hopefully I have enough fuel sorted for 500BHP
Phil

mmmm checking the fuel pressure may be interesting lol.
currently running a bosch 044 pupmp, and -6 fuel hose,
current injectors are 440cc bosch motorsport ones,

what injectors have you now gone to Phil?

Coops wrote:I can't remember these being mentioned before
just been looking on eGay and can find 60lb (630cc) but not 63lb ones, any links please???

60, 63, 600cc, 630cc, 660cc, for some reason different places call them different things.

There are loads available though. But basically yes it is the mototron/siemens/ etc 600c or thereabouts pencil style.

ie

http://www.ebay.co.uk/itm/60lb-Siemens- ... 19cd40d7a9

http://www.ebay.co.uk/itm/60-SIEMENS-DE ... 485b94db5c

Your 044 should be fine, assuming wiring and filter are up to the job.

I'm running the 044 pump and -6 delivery hose with -6 rail in a U shape like a std hotwire rail. (if i was to do it again, i would be a Y though)

What size pipe are you feeding the pump with? - I was told they dont suck very well and that you should make the large and free flowing - so i made mine -10

You can see the setup half way down here:
http://www.mez.co.uk/ms13-new.html

Does the pump sound like it's cavitating? (like a washing machine draining)

Coops wrote:mmmm checking the fuel pressure may be interesting lol.
currently running a bosch 044 pupmp, and -6 fuel hose,
current injectors are 440cc bosch motorsport ones,

what injectors have you now gone to Phil?

Is your Duty Cycle hitting 95% at high RPM or is it the AccelEnrichment then, as if its AE its not going to need bigger injectors, its probably a setting, or possibly a small bug in the Alpha code your running. Email me and we can change over to a newer Alpha if it is AE.

I bought these, very cheap!
http://www.ebay.co.uk/itm/290996394182? ... 1497.l2649

As Im modifying the fuel rails Im not worried that they are physically smaller as I think I can change the rails to suit, also fitting new connectors isnt an issue for that price,
Phil

at high rpm, there is no call to be using any accel enrichment.

Coops (and possibly Phil) I struggled with -6 fuel pipe to get good fuel pressure at all rpm/loads so have gone up to -10 feed to pump (bosch 044) and -8 to fuel rails. Although in theory -6 should be good enough (3/8 bore on flexi pipe) I found that on solid pipe sections and connectors the aperture for the fuel to flow through was smaller than 3/8 so caused a restriction. Also check the size and capability of your filters as I've seen some pretty small ones on poorly performing set-ups. Hope I'm not teaching you to suck eggs here etc!

Cobratone wrote:Coops (and possibly Phil) I struggled with -6 fuel pipe to get good fuel pressure at all rpm/loads so have gone up to -10 feed to pump (bosch 044) and -8 to fuel rails. Although in theory -6 should be good enough (3/8 bore on flexi pipe) I found that on solid pipe sections and connectors the aperture for the fuel to flow through was smaller than 3/8 so caused a restriction. Also check the size and capability of your filters as I've seen some pretty small ones on poorly performing set-ups. Hope I'm not teaching you to suck eggs here etc!

Ive made close to 700hp on a single -6 line from Bosch to rails on 4cyl turbo cars.

Certainly no harm in -8 though, but that is safe to well beyond 1000hp. ( from pump to rails )

One thing to note, not all -AN fittings carry the same bore size. As you say, the size generally denotes the ID of the flexible hose, but even this varies with hose type and brand, as well as actual fitting type.

But. Always ensure any gravity feed is adequate. I see some use -8, although Unless it's short and a good gravity feed, I'd prefer -10 or larger. You cant really go too big on the pump inlet if there is only gravity taking fuel there.

Always ensure pumps are wired sensibly and always see full alternator voltage.

Stevie,
just looking through ready to order some better injectors,
And spoke to fiveomotorsport who I bought my last set from in the states (the greens 440cc you recommended)
they are willing to ship to me again and do yet another deal if I tell them which ones I need as they list loads of siemen injectors:

The range of injectors they do: http://stores.ebay.co.uk/fiveomotorsport

The siemens ones they do: http://stores.ebay.co.uk/fiveomotorspor ... 34.c0.m322

They list too damn many, that's the problem lol

All I can say for sure is I use 8 of each and they seem to work good.

http://www.racetronix.biz/itemdesc.asp? ... 61&eq=&Tp=

http://www.racetronix.biz/itemdesc.asp? ... 62&eq=&Tp=

FiveO are listing one very similar, the 107961. Mine are 107962. And the injector nozzle is very different if their photos are to be believed.

Now this doesnt make sense. They are claiming the same part number, but the image clearly shows two very different injectors. One is the same as mine ( black ) the other not the same ( blue )

http://www.ebay.co.uk/itm/1-107961-Siem ... 3ccb33a976

http://www.ebay.co.uk/itm/1-60-LBS-FUEL ... 3ccf97679a

Set of 8, again black

http://www.ebay.co.uk/itm/8-Siemens-Mot ... 3f07fae503

Of course all the above assumes you're sticking with 600cc or thereabouts.

You could also give ASNU in the UK a shout, as they have a good range. US might still be cheaper though

http://www.asnuinjectors.co.uk/pdf/600.htm